Thread-trimmer for sewing-machines



l. KIEWICZ.

THREAD TRIMMER FOR SEWING MACHINES. APPLlcATloN mep ^Pn.1o, |913.nzngwen Dsc. 15, 1919.

3 SHEETS-SHEET 1.

Patented Apr. 27, 1920.

Fig; l.

AHys.

1. mfwlcz. THREAD TRIMMEFI FOR SEWING MACHINES.

APPLICATION FILED APR.' I0, |918. RENEWD DEC. I5, I9l9.

Patented Apr. 27, 1920.

3 SHEETS-SHEET 2.

FigA.

InvenIor. John Kiewicg I-w 76W@ Mam a Aw l. KIEWICZ.

THREAD TRIMMER FOR SEWING MACHINES.

APPLICATION FILED APR. 10. 1918. RENEwED Dic. 15,1919.

v 1,3 Patented Apr. 27, 1920.

3 SHEETS-SHEET 3.

UNITED STATES PATENT OFFICE.

JOI-IN KIEWICZ, OF BOSTON, MASSACHUSETTS, ASS'IGNOR TO THE REECE BUTTONHOLE MACHINE COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF MAINE.

THREAD-TRIMMER FOR SEW'INGr-MACHINES.

Application filed April 10, 1918, Serial No. 227,622.

To all whom t may concern:

Be it known that I, JOHN Kmwioz, a citi- Zen of the United States,residing at Boston, county of Suffolk, State of Massachusetts, haveinvented an Improvement in Thread- Trimmers for Sewing-Machines, ofwhich the following description, in connection with the accompanyingdrawing, is a specification, like characters on the drawing representinglike parts. f

This invention relates to sewing machines and particularly tobuttonholesewing machines, and the object of the invention is to providea novel device for severing the n needle 8.

under thread and stay-cord close to the work at the end of the stitchingoperation on each buttonhole. The device herein shown is in somerespects similar to that illustrated in my co-pending application Se.No. 203,889, filed November 26, 1917, and is in the nature of animprovement on said device.

The device illustrated in said application comprises two jaw memberscarried by the clamp plate which is removable from the frame, means tomove the jaw members into position to grip the under-thread and staycordbeneath the work at the end of the stitching operation and then toretract said closed jaw members so as to draw out a length of both thestay-cord and the underthread, and a knife which is operative after thejaw members have thus been retracted to cut the under-thread andstay-cord close to the work. n

In my present invention I retain the two jaw members,but construct themso thatthey operate vnot only to draw out the underthread and stay-cord,but also'to cut the latter, and I have also simplified the ymechanism:for operating the jaws. y p v In order to give an understanding ofmyinvention, I have illustrated in the drawings a selected embodimentthereof which will now be described, after which the novel features willbe pointed out in the appended* claims. v

In the drawings, Figure 1 is a side view of a portion of the sewingmachine having my improvements applied thereto;

Figs. 2, 3, 4f and 5 are plan views of the clamp plate with thethread-cutting` mechanism thereon, said views showing the mechanism indifferent relative positions;

Fig. 6 is an underside view of the front Specification of LettersPatent.

Patented Apr. 27, 1920.

Renewed December 15, 1919. Serial No. 345,124.

end of the bed-plate showing the ends of the actuating levers;

F ig. 7 is an enlarged section on the line nur, rig. e;

the manner ,in which the block 11 of the work-holding means vretains thejaw members in their retracted position.

1 indicates the ybed-plate of the sewing machine from which rises thehead or overhanging arm- 2 in which reciprocates the usual needle-bar lwhich carries the upper Situated beneath the bed-plate 1 .is anunder-thread-handling mechanism of any usual type `which is indicatedgenerally by 5 and which is provided with the throatplate 12 having theaperture 18 through which the under-thread 6 and stay-cord 7 aredelivered.

The work in which the buttonhole is being formed is indicated at lw andis held during the sewing operation by work-holding means of any usualtype which is given its feeding movement during the stitching on abuttonhole by the usual feed cam 42. The work-holding means is hereinillustrated as comprising a clamp-plate 8 on which the work rests andwork-clamps 9 that clamp the work to the plate, said work clamps being,carried by arms 10 supported by a block 11 that is pivotally connectedto the clamp-plate 8 so as to allow the work clamps to close onto thework or to be opened to release the work, all as usual inbuttonhole-sewing machines.

Since the present invention relates solely to the device for cutting andtrimming the under-thread and stay-cord close to therwork at the end ofthe stitching operation. on each buttonhole, I have not thought itnecessary either to illustrate or describe further the buttonhole sewingmachine.

My improved under-thread and stay-cordtrimming mechanism comprises twojaw members 14 and 15 which are situated directly above the clamp-plate8 and between the latter and the work w and which are Y pivotallyconnected together by the pivotal stud 16, said stud extending throughand beneath the jaw members and the lower end thereof operating Vin aguiding slot 17 Y formed in the clamp-plate 8. The jaw members thus arecapable of having a bodily movement toward and from the throat-plate 12and also an opening and 'closing movement about the pivot 16.

The jaws 14 and 15 are each provided with a thread-receiving notch 26and with a beak 27, the beaks being so arranged that when the jaws areclosed they will overlap each other.

During the sewing operation on the buttonhole the jaws 14 and 15'y arein their retracted open position shown in Fig. 2, in which position theyare situated between the throat-plate 12 of the under-thread mechanismandJ the front of the machine. At the' end of the stitching on abuttonhole the two jaws 14 and 15 ai'e moved bodily toward thethroat-plate while in their open relation so as to carry them into theposition shown in Fig. 3. During this movement the beaks 27 pass eitherside of' the under-thread 6 and sta-y cord 7 that extend from the workthrough the throat-plate, so that said under thread and .stay-cord aresituated opposite the notches 26. The jaws are then closed suilicientlyto cause the beaks 27 to overlap slightly so that the notches 26 form aclosed aperture in which the under-thread and stay-cord are received.After the jaws have been thus closed they are moved backwardly bodilyinto the position shown in Fig. 4 thereby drawing out from the source ofsupply a length of under-thread and stay-cord, after 'which theunder-thread and stay-cord are cut close to the work. This isaccomplished by providing the notches 26 with cutting edges 28 and byproviding means forgiving the jaws a further closing movement, as shownin Fig. 5, so that the cutting edges 28 will act on the stay-cord andunderthread with a shearing cut thereby to sever them.

I will now describe the mechanism T prefer to employ for giving the aws14 and 15 the above-described sequence of movements.

The means T employ 'for holding the jaws in their retracted positionduring the stitch.- ing of the buttonhole is controlled by the workclamp, so that when the work-.cl amps 9 are raised to unclamp the workthe uws' will be moved 'forwardly fromthe position shown in Fig. 2 tothat shown in Fig. The upper end of the stud 16 is received in a slot 30formed in the end of a.l lever 31 which is pivoted to the clamp plate 3at 32. Said lever has a strut 33 connected thereto, the end of whichengages the block 11 oi3 the work clamp when said work clamp is inoperative clamping position. The lever 31. has an. arm 34 extendingtherefrom to which is connected a pulling spring V35 that tends to swingthe lever 31 to the right. So long as the worlrclamp 9 is lowered, thestrut 33 will engage. the block 11 and hold the jaws- 14 and 15 in theirretracted position againstv the action of the spring 35. Vhen theworkelamps 9 are raised to unclamp the work, then the lower edge of theblock 11 is carried above the end of the strut member 33 therebyreleasing the latter and allowing the spring 35 to move` the jawsforwardly into the position shown in Fig. 3.

The closing movemento'f the jaws is controlled by a lever 21 pivoted tothe frame at 22. This lever is provided with a pin 20 which operates ina slot 19 formed in the rear end 18 of the jaw 15 and also operates inan opening 24 formed in the rear end 23 of the jaw 14. The opening 24 isprovided with the inclined edge 25. The lever 21 is acted upon by aspring 36 which tends to swing it inwardly toward the right and therebymaintain the pin 20 at the inner end of the slot 19 and opening 24. Whenthe pin 2() is in this position the jaws are inopen relation, as shownin Figs. 2 and 3. After the jaws have been moved forwardly into theposition shown in Fig. 3 the lever 21 is swung backwardly, during whichmovement the pin 2() acts against the inclined wall 25 ot the opening 24and against the wall of the slot 19 thereby swinging the jaws into thepartially-closed position shown in Fig. 4. This is done while the awsremain in their forward position shown in Fig. 3 so that the beaks 27will pass behind the underthread and stay-cord, thus locking them in theopening formed by the notches The length of the slot 19 is such thatwhen the swinging movement of the lever 21 has brought the pin 20 to therear end of the slot, the jaws will be in their partiallyclosed positionshown in Fig. 4. The lever 21 has a range of movement greater thannecessary to bring the pin 20 to the rear end of the slot 19, so thatduring the further swinging movement of said lever, the in 20 will actagainst the end oil the slot 19 and will thereby move the jaws bodily tothe left into the position shown in Fig. 4, this movement beingaccomplished while the jaws are retained in their partially-closedposition. This bodily backward movement of the jaws results in pullingout a length of under-thread and. 'stay-cord, as shown in Fig. 4, andduring such movement the stud 16 travels backwardly in the slot 17.

The meansjfor giving the lever 21 its backward swinging movement issimilar to the corresponding means shown in my abovementioneflfio-pending application, and -it comprises an elbow-lever 37 pivoted tothe iinderside'oi1 the bed plate at 52 and which is acted upon by aspring 53 that normally holds itin the position shown in Fig. 5. One arm54 of thiselbow-lever is engaged andV actuated hya lever 39 pivotedtoturn about a stud 40.V and the other arm 55 lof said elbow-leveradapted to contact with a .pin or projection 38 depending from the lever21. The swinging movement of the lever 39 will, therefore, operatethrough the elbowlever 37 to give the lever 21 the necessary rearwardswinging movement. The lever 39 is actuated by a cam 41 which is rigidwith the usual main cam 42 of the buttonhole sewing machine by which thework-holding means is given its feeding movement. This cam 41 is similarto the corresponding cam illustrated in my co-pending application and isconstructed so that at the proper time in the cycle of operations itwill actuate the lever 39 thereby to cause the rearward movement ofthelever 21.

For cutting the stay-cord after the jaws have been pulled backwardlyinto the position shown in Fig. 4, I employ a lever 43`also pivoted at40 and acted upon by the cam 41, the end 44 of said lever being adaptedto engage a depending finger 45 extending from the end 23 of the jaw 14.The shape of the cam 41 is such that after the lever 39 has beenactuated thereby to cause the jaws 14 and 15 to be retracted into theposition shown in Fig. 4, the lever 43 will be actuated to bring the end44 thereof against the finger 45 thereby giving a swinging movement tothe jaw 14 into the position shown in Fig. 5 which will cause theshearing edges 28 to cooperate to cut the underthread and stay-cord. Theaperture 24 is made large enough so as to permit this cutting movementof the jaw 14.

The jaw 14 is shown as having a wedgeshaped projection 46 which isadapted to enter under a hold-down member 47 carried by the jaw 15, thepurpose of this being to insure that the cutting edges 28 will be heldin shearing relation during the cutting operation.

The jaws 14 and 15 are normally held open by means of a spring 4S and anadditional spring 49 is provided which only becomes compressed after thejaws are closed. The spring 49 is relatively stifl'I and the purpose ofit is to give the jaws an initial opening movement after the lever 43has been operated to effect the severing of the underthread andstay-cord.

In actual practice the jaws will be covered by a cover-plate 50, saidplate being so shaped that it will cover the jaws when they are in theirretracted position, but when the jaws are moved into the position shownin Fig. 3 they' will project slightly beyond the edge 51 of the plate.The location of the edge 51 is indicated by the dotted line 51 in Figs.2, 3 and 4. The work w rests on the plate 50 and said plate, therefore,protects the work from the thread-trimming mechanism.

While I have herein illustrated a selected embodiment of the invention,I do not wish to be limited to the constructional features shown.

I claim:

1. In a sewing machine, the combination with work-holding means, ofstitch-forming mechanism including under-thread-handling mechanism, apair of pivotally-connected jaw members, each having a threadreceivingnotch and a beak, means operative at the end of a stitching operation tomove the jaw members into position to engage the thread, means topartially close said jaws thereby to bring the beaks into overlappingrelation and to inclose the thread in the notches and then to move thejaws bodily to draw out a length of thread, and means to give the jaws aiinal closing movement thereby to sever the thread.

2. In a sewing machine, the combination Y with work-holding means, ofstitch-forming mechanism including under-thread-handling mechanism, apair of pivotally-connected jaw members situated beneath the work andeach provided with a thread-receiving notch and a beak, means operativeat the end of a stitching operation to move said jaws into position toengage the underthread beneath the work, means to partially close saidaws thereby to bring the beaks into overlapping relation and to inclosethe under-thread in the notches of the jaws and then to move the jawsbodily to draw out a length of under-thread, and means to give said jawsa iinal closing movement thereby to sever the thread.

3. In a sewing machine, the combination with work-holding means, ofstitchforming mechanism including under-threadhandling mechanism, a pairof pivotallyconnected jaw members carried by the workholding meansbeneath the work, each jaw member having a thread-receiving notchprovided with a cutting edge and a beak, means operative at the end of astitching operation to move the jaws into position to engage theunder-thread, means to partially close said jaws thereby to bring thebeaks into overlapping relation and then to move the jaws bodily anddraw out a length of under thread, and means to give said jaws a finalclosing movement thereby to sever said thread.

4. In a sewing machine, the combination with a frame, of work-holdingmeans removable therefrom and comprising a clamp plate, stitch-formingmechanism including an under-thread-handling mechanism provided with athroat-plate, a pair of pivotally-connected jaw members carried by theclamp plate, and each provided with a notch having a cutting edge and abeak beyond the notch, means operative at the end of a stitchingoperation to move said jaws on the clamp plate into thread-engagingposition, means to partially close said jaws thereby to bring the beaksinto overlapping relation and then to move the jaws bodily on the clampplate to draw out a length or thread from the throat-plate, and means togive said jaws a final closing movement thereby to sever the thread.

5. In a sewing machine, the combination with work-holding means, ofStich-forming mechanism including under-thread-handling mechanism, apair oi' pivotally-connected jaw members carried by the workholdingmeans and each provided with a. notch having a cutting edge and a beakbeyond the notch, means operative at the end of the stitching operationto carry the jaw members into thread-engaging position, a lever actingon the jaw members and operating first to partially close said jawsthereby to inclose the thread in the thread-receiving notches and thento move the jaws bodily to draw out a length of under-thread, and meansacting on one jaw to complete the closing movement of the jaws therebyto sever said thread.

6. In a sewing machine, the combination with worlvholding means, oistitch-forming mechanism, a pair of pivotally-con-nected jaw members,each having a thread-receiv ing notch provided with a cutting edge and abeak beyond the notch, one jaw member having at its rear end an inclinedslot, and the other an opening provided with an oppositely-inclinededge, a pivoted lever` having a pin extending through said slot andopening, means to swing the lever to carry the pin to the rear end ofthe slot and cause it to act against the inclined side of said openingwhereby the jaws are closed sufi'ciently to cause the beaks to overlapso that the thread is inclosed in thenotches, said means operating togive the lever -a further swinging movement thereby to retract the jawsbodily, and means acting on the jaw having the opening to give it afurther closing movement thereby to sever the thread.

In testimony whereof, I have signed my name to this specification.

JOHN KIEVICZ.

